1. Field of the Invention
The present invention relates to hydraulic motor assemblies and, more particularly, to hydraulic motor assemblies mounted within a wheel and rotatably carried on a spindle.
2. Description of the Related Art
The mounting of a hydraulic motor within a wheel wherein the hydraulic motor is rotatably carried on a spindle is known in the art. Typically, such hydraulic motors drive the rotation of the wheel within which they are mounted when the motor is operating and allow the wheel to freely rotate when the motor is not providing a driving force. The spindle is often integrally formed with a knuckle that can be rotatably engaged with a vertically extending kingpin. The rotatable engagement of the knuckle and kingpin allow the wheel to be a steerable wheel.
Hydraulic fluid must be communicated to and from the hydraulic motor and hydraulic passages are typically formed in the spindle and knuckle to provide for this communication of hydraulic fluid. For example, it is known to provide a plurality of hydraulic passages in such an integrally formed knuckle and spindle wherein each of the passages includes both an axially extending section and a laterally extending section. The axially extending sections extend substantially parallel with the central axis defined by the spindle and have one end in communication with the hydraulic motor assembly. The opposite end of the axially extending sections are in communication with a corresponding one of the laterally extending sections. The laterally extending sections each extend laterally outwardly from the axially extending sections to a port located on the outer surface of the knuckle. These laterally extending sections of the hydraulic passages are arranged at differing angles without any of the laterally extending sections being arranged parallel with each other. This arrangement of the hydraulic passages, while effectively communicating hydraulic fluid to the hydraulic motor assembly, is relatively complex and expensive to manufacture.